Granulated enzyme products are extensively used in the detergent, food, medical, leather and textile industries, as well as in the production of processed marine products, and a variety of commercial products suitable for specific purposes are available.
A granulated enzyme has the following advantages over an enzyme powder: (1) high flowability, (2) ease of measuring, (3) no sticking to the walls of a container, (4) no formation of agglomerates, (5) improved appearance, and (6) high stability. If a granulated enzyme is used in a medicine or detergent, it must meet additional requirements such that it should easily disintegrate in liquids and have sufficient strength to withstand the usual handling of granules.
Conventional enzyme granules are produced by charging a mixture of an enzyme powder and water into a granulator, and granulating the powder either in the presence or in the absence of a binder etc. During the granulation, the charged mixture will stick to the walls of the granulator, and the resulting deposit is not only undesirable from a hygienic viewpoint but it also causes problems in the carrying out of the granulation of the powder smoothly. A method of avoiding this problem, by using a properly adjusted amount of water, is effective only in a limited range, and it often occurs that granules grow too fast to enable precise control over the granule size.
It is known that fibrous cellulose is used as an ingredient for a granular composition containing an enzyme to improve granulation characteristics, as described in U.S. Pat. No. 4,106,991. However, the resulting granular composition is still fragile and insufficient in toughness against fracture. Further, as the content of enzyme in the granular composition is increased, it becomes more difficult to avoid sticking of the charged mixture to the walls of the granulator, and therefore it is necessary to add a very large amount of fibrous cellulose in the composition in order to minimize sticking.